自己用PHP封装了一个DB数据库 mysql 的类

<?php        // 配置数据库define('DB_HOST', '127.0.0.1');   //服务器地址define('DB_USER', 'root');   //用户名define('DB_PASS', '');  //密码define('DB_DATABASENAME', 'fenxiao'); //数据库class Dbmysql{   /**变量**/private $tablename=""; //表名private $fieldname="*";private $conn;private $where;private $sql;function __construct($tablename){//生成一个连接$this->conn = mysql_connect(DB_HOST, DB_USER, DB_PASS) or die("connect failed" . mysql_error());  //选择数据库mysql_select_db(DB_DATABASENAME, $this->conn); //设置编码格式mysql_query("SET NAMES utf8");//var_dump($conn);$this->tablename=$tablename;}//设置sql语句private function setsql($sql){$this->sql=$sql;}//设置条件语句public function where($where){$this->where=" where ".$where;return $this;}//按指定字段public function field($keyword){$this->fieldname=$keyword;return $this;}//设置连接查询表public function table($table1,$table2,$field,$bool){$this->tablename="$table1 LEFT JOIN $table2 ON $table1.$field$bool$table2.$field";//print_r($this->tablename);return $this;}//设置多表查询public function addtable($table1,$table2,$field,$bool){$this->tablename.=" LEFT JOIN $table2 ON $table1.$field$bool$table2.$field";//print_r($this->tablename);return $this;}//设置连接查询表##SELECT * FROM 【wx_order LEFT JOIN wx_shopcar ON wx_shopcar.oid=wx_order.oid and wx_order.uid=wx_shopcar.uid LEFT JOIN wx_goods ON wx_shopcar.gid=wx_goods.gid】 WHERE wx_order.oid=1 and wx_order.uid=3public function settable($sql){$this->tablename=$sql;//print_r($this->tablename);return $this;}//查询所有数据库 以数组形式输出public function select(){  /*** 查询数据库中所有的数据**/$arr=array();//执行sql语句$result = mysql_query("select ".$this->fieldname." from ".$this->tablename.$this->where, $this->conn); while ($row = mysql_fetch_assoc($result)) {array_push($arr, $row);}return $arr; }//搜索指定字段数据public function find(){//执行sql语句$result = mysql_query("select ".$this->fieldname." from ".$this->tablename.$this->where, $this->conn); $result = mysql_fetch_assoc($result);return $result;}//增加数据到数据库public function add($data){$keysql='';$valuesql='';foreach ($data as $key => $value) {$keysql.=",`$key`";$valuesql.=",'$value'";}$keysql=substr($keysql, 1);$valuesql=substr($valuesql, 1);$result=mysql_query("insert into `".$this->tablename."` ($keysql) VALUES($valuesql)");$id=mysql_insert_id();//print_r("insert into `".$this->tablename."` ($keysql) VALUES($valuesql)");return $id;}//修改数据库的内容public function save($data){$keysql='';$valuesql='';foreach ($data as $key => $value) {$keysql.=",`$key`='$value'";}$keysql=substr($keysql, 1);//print_r($keysql);//echo "<br>";$result=mysql_query("UPDATE `".$this->tablename."` SET ".$keysql.$this->where);//print_r("UPDATE `".$this->tablename."` SET ".$keysql.$this->where);return $result;}##删除数据public function delete(){$result=mysql_query("DELETE FROM $this->tablename $this->where");//print_r("DELETE FROM $this->tablename $this->where");return $result;}}/*** mysql_fetch_row: 返回单列的各字段 [0]=>"111"* mysql_fetch_field: 取得字段信息。[0]=>   ['name']=>   object* mysql_fetch_array    返回数组资料。 [0]=>"asasds"   ['name']=>*/?>

来自： http://my.oschina.net/Peron/blog/552601